Magnetically controlled proportional fluid amplifier

ABSTRACT

A proportional fluid amplifier that utilizes a magnetic fluid as control means for the proportional amplification therein. The magnetic fluid is placed in one of the two control ports of the amplifier and under the influence of an externally applied magnetic field is made to partially block the control port which, in turn, creates a low pressure region that causes switching of the power stream from one output channel to another. The magnitude of the externally applied magnetic field is proportional to the amount of blockage effected by the magnetic fluid in the control port, and thus to the magnitude of the low pressure region created therearound. In this way, the low pressure region can be controlled directly by external electrical apparatus and the power stream can be deflected to any one of a plurality of output channels as desired.

United States Patent Harris et al.

[1 1 3,672,387 [451 June 27, 1972 [54] MAGNETICALLY CONTROLLED PROPORTIONAL FLUID AMPLIFIER 12 Inventors: Fred 1'. Harris, Rockville, Md.; Edwin L. Resler, Jr., Ithaca, NY.

[73] Assignee: The United States of America as represented by the Secretary oi the Army [22] Filed: Oct. 1, 1970 211 Appl. No.: 77,166

Primary Examiner-William R. Cline Attorney-Harry M. Saragovitz, Edward J. Kelly, Herbert Berl and Saul Elbaum [5 7] ABSTRACT A proportional fluid amplifier that utilizes a magnetic fluid as control means for the proportional amplification therein. The magnetic fluid is placed in one of the two control ports of the amplifier and under the influence of an externally applied magnetic field is made to partially block the control port which, in turn, creates a low pressure region that causes switching of the power stream from one output channel to another. The magnitude of the externally applied magnetic field is proportional to the amount of blockage effected by the magnetic fluid in the control port, and thus to the magnitude of the low pressure region created therearound. in this way, the low pressure region can be controlled directly by external electrical apparatus and the power stream can be deflected to any one of a plurality of output channels as desired.

4 Claims, 5 Drawing Figures MAGNETICALLY CONTROLLED PROPORTIONAL FLUID AMPLIFIER RIGHTS OF GOVERNMENT The invention described herein may be manufactured, used, and licensed by or for the United States Government for governmental purposes without the payment to us of any royalty thereon.

BACKGROUND OF THE INVENTION 1 Field of the Invention This invention relates to fluid amplifiers and, more particularly, to proportional fluid amplifiers whose power stream is controlled by magnetic means.

2. Description of the Prior Art Proportionalamplifiers are themselves old in the fluidic art, referring generally to fluid amplifiers that have a plurality of output channels through one of which flows the power stream from the input channel. The output channel selected for exhausting the power stream is generally dependent upon the relative pressures in the control jets that impinge upon the power stream from the control ports of the fluid amplifier. As is well known in the art, the power stream will tend to deflect towards the control port that establishes the lower pressure region. Thus, the power stream can be caused to exit along any one of a plurality of output channels depending upon the pressure gradient between the two control ports. Means for providing a varying pressure in one or both of the control ports has heretofore been primarily limited to separate fluidic sources that are pumped and controlled independently of the power stream or mechanical valving arrangements which increase or reduce the flow and thus the pressure in one or both of said control ports. The aforedescribed control means become impractical when mechanically inaccessible areas need to be reached and controlled in a minimum amount of time. Additionally, the mechanical apparatus is subjected to deterioration and wear, while any additional fluidic apparatus adds significantly to the complexity and cost of the system.

Accordingly, it is the primary object of the present invention to provide a proportional fluid amplifier that utilizes magnetic control means to direct the power stream out of one of a plurality of output channels.

A further object of the present invention is to provide a simple control means to a proportional fluid amplifier that is remotely controllable by a magnetic field.

Another object of the present invention is to provide a proportional fluid amplifier that utilizes the characteristics of a magnetic fluid to provide simple control means for switching the output of the amplifier.

SUMMARY OF THE INVENTION Briefly, in accordance with the invention, a magnetically controlled proportional fluid amplifier is provided that utilizes the characteristics of a magnetic fluid as control means for switching the output of the amplifier. In a preferred embodiment form, the amplifier comprises a plurality of output channels located downstream from an interaction region into which a power stream flows from the input channel. A pair of control ports are located diametrically opposed at the interaction region of the amplifier. The magnetic fluid is placed in one of the control ports in the vicinity of a pair of pole pieces which are arranged so as to partially obstruct the opening from the control port to the interaction region. The application of a magnetic field to the pole pieces will cause the magnetic fluid to be drawn towards the pole pieces. The magnetic fluid will then tend to conform to the lines of greatest magnetic flux between the two pole pieces. This results in a reduction of the cross-sectional area of the control port which in turn creates a low pressure region causing the power stream in the amplifier to switch from one output channel to another. The magnitude of the applied magnetic field is proportional to the pressure change in the control channel, since, as the magnetic field is increased, more and more of the magnetic fluid will be drawn to the pole pieces and will block off a greater portion of the control port. In this way, the varying magnetic field can be utilized to select directly the output channel through which the power stream exhausts.

BRIEF DESCRIPTION OF THE DRAWINGS The specific nature of the invention as well as other objects, aspects, uses, and advantages thereof will clearly appear from the following description and from the accompanying drawings, in which:

FIG. 1 illustrates a preferred embodiment of the proportional fluid amplifier of the present invention;

FIG. 2 presents a cross-sectional view of the device in FIG. 1 taken along the lines 22;

FIG. 3 is the same view as shown in FIG. 2 in a different mode of operation;

FIG. 4 is the same view as FIG. 3 in another different mode of operation; and

FIG. 5 is the same view as FIG. 4 in another mode of operation.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 is shown in a vertical view a proportional fluid amplifier 10 in accordance with the teachings of the present invention. Amplifier 10 comprises an input channel 12 through which a fluid power stream is directed, an interaction region 13, a plurality of output channels 14, l6, l8 and 20, and a pair of control ports 22 and 24 that are directed to exhaust through openings 17 and 15, respectively, to interaction region 13. In normal operation, a fluid power stream entering input channel 12 will exhaust through one of said output channels 14, l6, 18 or 20, depending upon the pressure gradient extending from opening 15 of control port 24 to opening 17 of control port 22 across interaction region 13. For example, if a low pressure region occurs at opening 15 of control port 24, the power stream entering input channel 12 will likely exhaust through output channel 14. As the pressure increases at openings 15, or alternatively decreases at opening 17, the power stream will switch from output channel 14 to output channel 16 and, if the pressure gradient continues to vary in the same manner, will eventually switch from output channel 16 to output channel 18 to output channel 20, as is well known in the art.

A magnetic polepiece 26 is shown in FIG. 1 located within control port 22. Pole piece 26 is placed through a hole in the front cover plate of amplifier 10 to prou'ude inwardly and partially block control port 22. Diametrically opposed to pole piece 26 is a symmetrical pole piece 30, not seen in this view, that is placed through another hole from the opposite side of control port 22. Below pole piece 26 is located a receptacle 36 whose function will become more apparent hereinafter. The configuration of pole pieces 26 and 30 is more apparent in FIG. 2 which shows a cross-sectional view of control port 22 taken along lines 22 of FIG. 1. It is seen in FIG. 2 that pole pieces 26 and 30 are diametrically opposed within wall 28 of control port 22. It is understood that while wall 28 is shown in circular cross-section, any appropriate cross-section may be feasible. Between pole pieces 30 and 26 is a slight void as defined by area 34. A magnetic fluid 32 is disposed within receptacle 36 that is in communication with area 34 via an opening 38. Magnetic fluid 32 is comprised characteristically of a colloidal suspension of submicron size ferrite particles in a carrier fluid such as kerosene, and has the property of conforming to the flux lines of an applied magnetic field. For a more complete discussion of such fluids, reference is made to an article by R. E. Rosensweig, entitled "Magnetic Fluids, which appeared at pages 48-56 in the July 1966 issue of International Science and Technology, published by Conover Mast Publications in New York. Magnetic fluid 32 remains within receptacle 36, essentially under the influence of gravity, prior to the application of a magnetic field to pole pieces 26 and 30.

As seen in FIG. 3, the application of a small magnetic field to pole pieces 26 and 30 will act to draw a portion 32A of magnetic fluid 32 through opening 38 to area 34 between pole pieces 26 and 30. Magnetic fluid 32A will tend to conform to the lines of greatest flux existing between pole pieces 26 and 30 and will remain in place as long as the applied magnetic field remains constant. The result, as evident in FIG. 3, is a reduced cross-sectional area 34 within wall 28, which will necessarily result in a lower pressure at opening 17 of control port 22 in amplifier 10. Thus, if we assume in FIG. 1 that initially the power stream is exhausting through output channel 14, then the condition as represented in FIG. 3 would result in the switching of the output stream from channel 14 to channel 16.

Referring now to FIG. 4, the same cross-section of wall 28 within control port 22 is shown with an applied magnetic field of greater magnitude than was present in FIG. 3. The increased magnetic field existing between pole pieces 26 and 30 will act to draw more magnetic fluid from receptacle 36 through opening 38 to area 34. This, of course, will result in a further reduction of the cross-sectional area 34 within wall 28 of control port 22 which, in turn, will create an even lower pressure region at opening 17, causing the power stream of amplifier 10 to switch from output channel 16 to output channel 18. H0. in the sequence shows the results of an even increased magnetic field applied to pole pieces 26 and 30 than was applied in FIG. 4. An even larger portion 32A of magnetic fluid 32 is drawn from receptacle 36 in response to the increased field strength between pole pieces 26 and 30. This results in a further reduction of cross-sectional area 34 within side wall 28 of control port 22 creating a lower pressure region at opening 17. This lower pressure at opening 17 causes the control stream exhausting through output channel 18, a result of the configuration shown in FIG. 4, to switch and exhaust through output channel 20 of amplifier 10.

It is seen that we have provided a simple device for controlling the power stream of a proportional fluid amplifier. The magnetic fluid interposed within control port 22 does not interact directly with the power stream that is under its control. The amount of cross-sectional area 34 of control port 22 that is reduced or increased is a direct function of the magnitude of the applied magnetic field to the pole pieces within control port 22. In this way, the pressure in the region of the opening of the control port can be adjusted in increments to provide a simple means for switching the power stream of one output channel to another. This invention is advantageous since the magnetic field can be quickly introduced into a closed system to reach otherwise inaccessible areas to control the flow of the power stream in a minimum amount of time. While the magnetic switching means have been shown and described located within one control port of a fluid amplifier,

it is appreciated that if such means were placed in both control ports, further advantages would result in tenns of accuracy and controllability of the pressure gradient within the interaction region. The position of the pole pieces in wall 28 of control port 22 can be varied so as to achieve the maximum effect of the changing magnetic field in conjunction with the disposition of the magnetic fluid therein. Probably the most advantageous position of the pole pieces is right at the junction of opening 17 and interaction region 13, flush with the extension of the wall that confines the power stream, although it is to be understood that we do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

We claim as our invention: 1. A magnetically controlled proportional fluid amplifier, comprising:

a. an input channel through which a non-magnetic fluid flows in a power stream; b. an interaction region that receives said power stream from said input channel; c. a plurality of output channels located downstream of said interaction region; d. first and second control ports oppositely directed towards and in communication with said interaction region; and e. means located within said first control port for selectively switching said power stream to exhaust through one of said output channels, said switching means comprising a magnetic fluid and means for introducing a magnetic field that controls the disposition of said magnetic fluid within said first control port, such that upon the introduction of a magnetic field said magnetic fluid partially blocks said first control port to create a low pressure region in said interaction region whereby said power stream is caused to switch between a pair of said output channels.

2. The invention according to claim 1 wherein said switching means further comprises a pair of pole pieces located within said first control port and in the vicinity of said magnetic fluid for receiving said magnetic field such that upon the application of said magnetic field, said magnetic fluid is drawn towards said pole pieces so as to partially fill the void therebetween.

3. The invention according to claim 2 wherein the selection of one of said output channels through which said power stream exhausts is proportional to the magnitude of said magnetic field that is applied to said pole pieces.

4. The invention according to claim 3 wherein said pair of pole pieces are located diametrically opposed at the opening of said first control port to said interaction region.

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1. A magnetically controlled proportional fluid amplifier, comprising: a. an input channel through which a non-magnetic fluid flows in a power stream; b. an interaction region that receives said power stream from said input channel; c. a plurality of output channels located downstream of said interaction region; d. first and second control ports oppositely directed towards and in communication with said interaction region; and e. means located within said first control port for selectively switching said power stream to exhaust through one of said output channels, said switching means comprising a magnetic fluid and means for introducing a magnetic field that controls the disposition of said magnetic fluid within said first control port, such that upon the introduction of a magnetic field said magnetic fluid partially blocks said first control port to create a low pressure region in said interaction region whereby said power stream is caused to switch between a pair of said output channels.
 2. The invention according to claim 1 wherein said switching means further comprises a pair of pole pieces located within said first control port and in the vicinity of said magnetic fluid for receiving said magnetic field such that upon the application of said magnetic field, said magnetic fluid is drawn towards said pole pieces so as to partially fill the void therebetween.
 3. The invention according to claim 2 wherein the selection of one of said output channels through which said power stream exhausts is proportional to the magnitude of said magnetic field that is applied to said pole pieces.
 4. The invention according to claim 3 wherein said pair of pole pieces are located diametrically opposed at the opening of said first control port to said interaction region. 